This section of Galatians highlights our former status in order to emphasize why it would be so foolish to go back to law works and thus bondage under the hostile powers of darkness. It seems that the Galatians did not clearly understand what is at stake. In the applications, passages are cited that show how, as unconverted, we were under the jurisdiction of the powers of darkness. This is changed through the gospel when we come to Christ. Finally, Jesus' "yoke" of perpetual Sabbath rest is contrasted with the "yoke of bondage."
Handouts available here:
https://www.ggf.church/sermons/sermon/2013-10-20/slaves-under-guardians-stewards-and-the-stocheia-galatians-4:1-3
Video courtesy of Gospel of Grace Fellowship.